Retarding device.



W. SIMONSSON.

RETARDING DEVICE.

APPLICATION FILED MAR-25| |911. RENEWED DEC. 12,1916l Patented June 26,1917.-

me :mums Persns sa. ruoraumo.. wAsulNcruN. n. c.

san

RETARDING DEVICE.

Application filed March 25, 1911, Serial No. 616,815. Renewed December12, 1916.

To all whom it may concern:

Be it known that I, lVrLi-IELM SrMoNssoN, a subject of the King ofSweden, and a resident of Brooklyn, in the city and State of New York,have invented certain lmprovements in Betarding Devices, of which thefollowing is a specification. 1

This invention relates to certain improvements in retarding devices, andmore particularly in that class of such devices which are of thedash-pot type, and the object of the invention is to provide a retardingdevice of this general character of a simple and comparativelyinexpensive nature, and of a strong, compact and durable construction,having certain features of novelty and improvement which are calculatedto insure reliable and effective operation and use of the device for along period of time without requiring repair or adjustment of itsoperative parts, and without excessive liability of deterioration orderangement of such parts from the accumulation of dust, hardcnedlubricant, etc.

The invention consists in certain novel features of the construction,and combinations and arrangements of the several parts of the improvedretarding device, whereby certain important advantages are attained.,and the device is rendered simpler, less expensive and more reliable andeffective, and otherwise better adapted and more convenient for use, allas will be hereinafter fully set forth.

The novel features of the invention will be carefully defined in theclaims.

In order that my invention may be the better understood l will nowproceed to describe the same with reference to the accompanyingdrawings, wherein 1 have illustrated several forms of retarding deviceembodying my improvements and especially designed for use in connectionwith weighing scales and other instruments of precision, in whichdrawings-4 Figure 1 is a sectional view taken centrally or axiallythrough one form of the improved retarding device;

Fig. 2 is an enlarged sectional view taken transversely through thedevice shown in Fig. 1;

Fig. 3 is an enlarged fragmentary section showing certain features ofconstruction to be hereinafter referred to;

Fig. l is an enlarged fragmentary section showing certain details of thepivotal sup- Speccation of Letters latent.

Patented J une 26, 1917.

Serial No. 136,545.

port for one of the members of the improved retarding device;

Fig. 5 is an axial section somewhat similar to Fig. 1, but showing aslightly different formation of the improved retarding device;

Fig. 6 is another axial section illustrating another vformation of theretarding device comprised within the present invention; and

Fig. 7 is a detached detail view showing a feature o-f construct-ion tobe hereinafter described.

The retarding deviceshown in Figs. 1 to 4f, inclusive, is of the wellknown dash-pot type having a cup or cylinder member 1 provided with anair chamber 2 wherein is housed the piston member 3, which is heldstationary upon the frame d, or other support, by means of a screw orbolt 5 which is passed centrally through said piston and through anapertured part of the frame member whereon the piston rests, and carriesa nut 6 at its lower end by means of which the piston may be lockedsecurely in place against accidental movement upon the frame.

The cup or cylinder memberl, as shown in these views, is provided with acentral upturned arm or projection 7, apertured in its upper end, asshown at 8, for the passage of a knife edge 9 the extremities whereofare mounted in the spaced forks of a link 10 0r equivalent part which ispremised to be coupled with or to form a part of one of the movingelements of a weighing scale or other instrument in connection wherewiththe improved retarding device is applied for use so that reciprocatorymovement shall be applied to move the cup or cylinder member verticallywith relation to the rigidly positioned piston member during theoperation of such instrument.

As clearly shown in Figs. 1, 2 and 3, the piston member 3 is madeslightly less in diameter than the diameter of the internal air chamber2 of the cup or cylinder member of the device, and in assembling theVparts, the piston member is rigidly positioned in axial alinement withthe direction of vmovement of the reciprocatory cup or cylinder member,whereby the difference in the diameters of the parts affords an absolutespace or clearance 11 between said members and surrounding or encirclingthe margin of the piston member, so as to provide a narrow or contractedvent or passage for the flow of airinto or out of the air chamber 2 ofsaid cut or cylinder' member when the cup or cylinder is movedrelatively to the piston during the operation of the improved retardingdevice.

By this construction and arrangement of the parts I am permitted toeliminate or minimize the effects of friction in the operation o-f theretarding device, and thereby materially to increase the accuracy andsensitiveness of the weighing scale or other instrument in connectionwith which the dash-pot is employed, it being evident that the absolutespacing of the members l and 3 in this manner permits of avoidingfrictional contact between them and assures the greatest freedom ofmovement of one member relatively to the other, at the same timedispensing altogether with the use of fiexible packing commonly providedfor closing the joint between the piston and cylinder, and alsodispensing with the special vent or duct commonly provided for the entryor escape of air into or from the cylinder, whose functions areperformed by the space or passage 1l in the device embodying myimprovements.

In the drawings I have shown the aperture 12 of the frame member 4through which the bolt or screw 5 is passed of a diameter slightlygreater than that of such bolt or screw, so as to facilitate a certainlateral adjustment of the piston member relatively to the frame member 4when said bolt or screw 5 is loosened, to the end that the piston membermay be readily and accurately alined with the axis of the cup orcylinder member during the assembling of the parts, so that the annularspace or clearance 1l may be maintained unobstructed, and frictionalcontact and binding of the parts may be avoided. The pivotal support orsuspension afforded by the knife edge 9 for the cup or cylinder member lalso permits a certain extent of free swinging movement 0f said memberlaterally with relation to the fixedly positioned piston member 3,whereby sticking or binding of the parts is avoided, and the provisionfor lateral movement of the suspended reciprocatory member thus affordedis of particular advantage where the instruments to which myimprovements are applied are subjected to sudden shocks or vibrationswhich, if both members of the retarding device were prevented fromlateral movement, would give rise to undesirable friction and binding ofthe parts.

In the construction of the improved retarding device, and moreespecially when the same is designed for use in connection with weighingscales and similar instruments of precision where great accuracy andsensitiveness is desirable, I prefer to proportion the parts in such amanner that the air chamber 2 of the cup or cylinder l has a capacitycalculated with respect to the area of the annular space or passage 11,the pressure tending to move one of the members relatively to the other,and the interval of time during which the retarding action is desired tobe exerted, and since, in many of the instruments of precision to whichmy invention is applicable, the elements whose movement is to be checkedor retarded have but short travel, I find it preferable in theconstruction of the retarding devices for application to suchinstruments, to give to the cylinder and piston a diameter ofcomparatively great width with respect to the travel Y of one memberrelatively to the other, and to form the air chamber of very smallcubical capacity, as compared with its diameter and the area of thepiston, so that in the operation of the device, the piston will rapidlyproduce a very high degree of compression of the air in the air chamber,and afford an extremely quick retarding action, irrespective of the factthat the margin of the piston is spaced from the wall of the cylinder.

I have also shown the piston member 3 provided upon its upper surfacewith an elevated edge wall or rim 14, within which a circular cavity orchamber l5 is provided which affords an air cushioning means operatingupon extreme downward movement of the cylinder or cup l, materially torelieve the shock which would be imparted to the moving elements of theweighing scale or other instrument to which the device is applied foruse, by the impact of the top wall of said cup or cylinder upon the topsurface of the piston.

As shown in the drawings, the cup or cylinder l is closed at its topagainst the entry of dust and the like which would tend by itsaccumulation within the chamber 2, to interfere with the desirablefreedom of movement of the members, and said cup or cylinder member isalso open at its base to afford access to said chamber 2, but I do notdesire to be understood as limiting myself in these particulars. Vfherethe open bottom is provided in the cylinder or cup, however, I havesometimes found it desirable to extend an auxiliary flexible closureover the same, as clearly shown at 16 in F ig. l, so as further to guardagainst the entry of dust and the like. As shown in this figure, theauxiliary closure is in the form of a cloth or other flexible diaphragm,having its central part affixed as indicated at A17 between the pistonand frame member 4, and having its edge portions clamped between thelower edge of the cylinder wall and a clamping ring or member 18 held inposition by screws 19.

I have also Shown the marginal or perimetral surface of the pistonmember 3 as made convex in Figs. l and 3, the same being provided with aparti-spherical surface 19, struck with a radius 20 from the axis of thepiston at a point midway of the width of said marginal or edge surfaceof the piston, whereby it will be evident that the piston is adapted toaccommodate itself automatically to allV ordinary rocking or pivotalmovements of the cylinder to the end that a substantially uniform areaof the space or passage l1 may be maintained at all times and binding orclogging of the piston within the cylinder further guarded against. Thisformation of the piston permits the space or passage l1 to be made ofcomparatively narrow width without undue liability of its becomingoccluded.

I have also shown the marginal or perimetral surface of said piston 3provided with an annular groove or channel 2l, encircling said pistonmidway of the width of its said parti-spherical surface 19, thisencircling groove or channel 21 affording an effective and reliable airpacking which impedes the flow of air through the space or passage l1during the operation of the improved retarding device, and permits ofmaking said space or clearance of greater area than would otherwise bepossible without lessening the retarding action exerted bv the device.

ln Fig. 5 I have shown an embodiment of my improvement very similar tothat above described, except that the forms of the piston and cylindermembers are slightly modified, and the lower edge portion of thecylinder wall has an inwardly directed annular part whose face presentedto the piston has such a convexity, as shown at 19a, as is calculated tocompensate for the rocking or pivotal movement of the lvcylinder toprevent occlusion of the space or passage 1l around the piston. Thisconvex surface 19a is also centrally grooved or channeled, as shown at21a for impeding the flow of air through said space or passage 11.

In Fig. 6 I have shown another embodiment of my improved retardingdevice which is in some respects alternative to that shown in Fig. l,particularly in that the piston is suspended and moves within thecylinder which is held stationary upon the frame and capable of lateraladjustment for alining it with the inclosed piston.

ln this form of the device, the cylinder la is held stationary within achamber 22 of the frame, and has a conical top wall provided with aflattened surface 23 engaged by a pendent skirt or projection 2i of theframe, which holds said cylinder in place while permitting the same tobe adjusted laterally of chamber 22 by means of adjusting screws 25. Theapex of the cylinder has a central boss Q6, wherein a graphite or otherantifriction bushing 27 is retained by means of a screw 2S in suchposition that the draft rod or link 30 which couples the piston with themechanism to be retarded may play through the bore of said bushing,there being sutlicient clearance between the bushing and said rod orlink to prevent undue friction a this point in the operation of thedevice. Three of the screws 95 are shown herein se disposed as to permitadjustment of the cylinder in all directions.

rlhe cylinder is open at its base for the passage of the lower end ofthe draft rod or link 30, which latter is thereby adapted for connectionwith suitable actuating means as, for example, a scale platform or otherload support. The central or intermediate part of said draft rod 30 has,within the chamber of said cylinder, spaced collars or enlargements 82,32 between which is loosely mounted the central part of the conical top33 of the bell-shaped piston member 3, the structure and arrangement ofthe parts being such that said piston member is balanced or suspendedfor free pivotal or rocking movement upon its connection with rod 30between said collars, in order that it may swing or move laterally toconform with the walls of the chamber of the cylinder during itsvertical movement therein, and thereby compensate for vibration andinaccuracies in the positioning of the parts.

The connections afforded by the upper and lower ends of the draft rod 30between the movable member of the retarding device, and the mechanism tobe retarded, and between said member and the actuating means beingalined axially with each other it will be apparent, however, that thelateral play of one member of the retarding device relatively to theother member is reduced to a minimum, in order that liability of contactor friction of the piston upon the cylinder wall may be eliminated to asgreat an extent as possible.

Vith regard to the annular space or passage 11 for the iow of air duringmovement of the piston, and the air packing groove or channel andsemi-spherical surface at the margin of the piston, the structure of thedevice shown in Fig. 6. is similar to that shown in Fig. l, exceptingthat said semispherical surface and groove or channel are produced in agraphite or other anti-friction ring 3a which is secured to and projectsfrom the margin of the piston member in position for contact upon thecylinder walls to reduce friction incident to excessive rocking orlateral movement of the piston. In the structure shown, the graphitering 34 is constructed in a plurality of segments as indicated in Fig. 7and these segments after having been plated with copper or the like aresecured in connected relation upon the piston member by means of solderas clearly indicated at 35.

From the above description of the invention it will be seen that theimproved retarding device constructed in accordance therewith is of anextremely simple and comparatively inexpensive nature, and isparticularly well adapted for use by reason of the efficiency andreliability of its operation, and of the absence of friction andnonliability of deterioration which renders the device especially wellsuited for use in connection with weighing scales and other instrumentsof precision Where accuracy of movement and durability are primeconsiderations, and friction is to be avoided in the greatest measurepossible, and it will also be obvious from the above description thatthe device is susceptible of some modiication without material departurefrom the principles and spirit of the invention, and for this reason Ido not desire to be understood as limiting myself to the preciseformation and arrangement of the several parts of the device herein setforth in carrying out my invention in practice.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. A dash pot retarding device having two relatively movable members,one of which is a cylinder having an air chamber open at one end of thecylinder, and the other of which is a piston Within said chamber' havingits margin separated'from the wall of the cylinder by a space whichlessens friction between the members and affords an air passage betweensaid air chamber' and the open end of the cylinder and adapted for theflow of air when one member is moved relatively to the other, and aclosure extended over the open end of the air chamber and adapted toexclude dust and the like and capable of iiexure to accommodate relativemovement of the members.

2. A dash pot retarding device having two relatively movable members,one of which is a cylinder having an air chamber closed at its upper endfor the exclusion of dust, and open at its lower end, and the other ofwhich is a piston housed within said chamber having its margin separatedfrom the wall of the cylinderl by a space which lessens friction betweenthe members and affords an air passage having communication with saidair chamber and is adapted for the iow of air when one member is movedrelatively to the other, a support having connection with the piston andextended through the open lower end of the air chamber, and a closurefor said lower end of the air chamber through which said support ispassed having its margins' connected with the cylinder wall and capableof exure to accommodate relative movement of the members.

3. A retarding device including two relatively movable members, one ofwhich is supported for rocking movement relatively to the other, one ofsaid members being a cylinder having an air chamber, and the othermember being a piston housed in said cylinder and adapted to traversethe air chamber when one member is moved relatively to the other, saidIpiston having its margins separated from the wall of the air chamber toafford a space which avoids friction and affords a passage for theescape of the contained air, and being of very large area as comparedwith the stroke of the movable member and with the cubic capacity of theair chamber, and operable upon movement of one member relatively to theother, to produce with great rapidity a high degree of compression ofthe air within said chamber.

4:. A dash-pot retarding device having two relatively movable members,one of which is a cylinder provided with an air chamber and the other ofwhich is a piston housed within said chamber, and a pivotal support forone of the members affording lateral movement thereof. during travel ofthe piston within said chamber to insure alinement of the members duringsuch travel, the piston having its margin provided with aparti-spherical surface concentric with the pivotal axis of saidsupport, and spaced from the cylinder wall to afford clearance betweensaid members and an air passage communicating with said air chamber andadapted for the flow of air during movement of one member relatively tothe other.

5. A retarding device including two members, one of which is movablerelatively to the other, one of said members being a cylinder providedwith a shallow air chamber of large diameter as compared Vwith thestroke of the movable member, and the other of said members being apiston adapted, when one member is moved relatively to the other, totraverse said air chamber of the cylinder, said piston having a diameterless than that of the air chamber to afford an annular airpassage'between its periphery and the cylinder wall adapted to avoidcontact of the piston on said wall and provide for the entry anddischarge of air into and from the air chamber, and of small area ascompared with that of the piston, calculated to retard the flow of airinto and from said chamber and to produce therein with great rapidity ahigh degree of compression when the movable member of the device isactuated.

6. A retarding device including two members, one of which is movablerelatively to the other, one of the members being a cylinder providedwith a shallow air chamber closed at its top but open at its base end ofbei being a piston adapted, when one member is moved relatively to theother, to traverse said chamber of the cylinder and having a diameterless than that of said chamber to afford an annular air passage betweenits periphery and the cylinder wall adapted to avoid contact of thepiston on said wall and to provide for the entry and discharge of airinto and from the air chamber, said annular passage being of small areaas compared with that of the piston, and calculated to retard the flowof air into and from said chamber and to produce therein with greatrapidity a high degree or' compression when the movable member of thedevice is actuated.

7 A retarding device including two members, one of which is movablerelatively to the other, one of the members being a cylinder providedwith an air chamber of large diameter as compared with the stroke of themovable member,` and the otherl member' being a piston adapted, when onemember is moved relatively to the other, to traverse said chamber oi'the cylinder and having a diameter less than that of said chamber toafford an annular air passage between its periphery and the cylinderwall for the entry and discharge of air into and from said air chamberand of small area as compared with that of said piston, calculated toretard the flow of air into and from said chamber and to produce thereinwith great rapidity a high degree of compression when the movable memberof the device is actuated, and parts extended oppositely from themovable member adapted, or connection, respectively, with an actuatingmeans, and

Copies of this patent may be obtained for with a mechanism to beretarded, and operable to maintain said movable member in alinement withits companion member to avoid contact of the piston upon the cylinu derwall.

8. A retarding device including two members, one of which is movablerelatively to the other, one of the members being a cylinder providedwith an air chamber of large diameter as compared with the stroke of themovable member, and the other member being a piston adapted, when onemember is moved relatively to the other, to traverse said chamber of thecylinder and having a diameter less than that of said chamber to affordan annular air passage between its periphery and the cylinder wall forthe entry and discharge of air into and Jfrom said air chamber and ofsmall area as compared with that of said piston, calculated to retardthe flow of air into and from said member and to produce therein withgreatv rapidity a high degree of compression when the movable member ofthe device is actuated, and parts extended oppositely from the movablemember, whereon said member is loosely supported, and adapted forconnection, respectively, with an actuating means, and with a mechanismto be retarded.

In witness whereof have hereunto signed my name this 6th day ot March1911, in the presence of two subscribing witnesses.

VILHELM SIMONSSON.

Witnesses:

W. E. LAwsoN, J. D. CAPLINGER.

Washington, D. C.

